AKD THE OTHER" ELE&ENTS OP &&otrp v. 197
Mobium and tantalum.*1 occur as acids in rare tninerals, and are
mainly extracted from tantalite and colufribite, -which are found in
Bavaria, Finland, North America, and in the TJrals. These minerals
are composed of the ferrous salts of niobic and tantalio acids; they
electric furnace, and considered 'it to- be moat infusible of the metals in, the series Pt»
Cr, Mo, U, W. and V (He also obtained a compound of vanadium and carbon). Tho
specific jgravity.of this *netftl is 6% It ia.of a groy-whlto colour, is not. decomposed by
water, and is not oxidised in mix, bud bums when strongly heated, and can be fused in a
current ol hydrogen (forming perhaps a compound with, hydrogen), It is insoluble in
hydrochloric acid, but easily dissolves in nitd? Acid, and whom'fused with caustic Boda {6
forms sodium vanadato.
As regards the salts of vanadid add, throe different classes ore known; the flrst
correspond with, metavanadio add, VMba-'MaOVjOis, the Beoond%oorrespond with tho
dichromateB—that is, have the composition V^M^On, wjiioh is equal to MjjO+aVjjOi
~*and -the third correspond -with orthbvanadio acid, VMS04 •or OMj.OH-'VaOfi. The latter
aro formed when vanadio, anhydride is fused.with an excess of an alkaline carbonate.
Vanadio add gives the Bo-oaUed ' oomple»' acids (wbiph are considered more fully to
Chapter XXI. in apoaldng ol Mo and W)—i.u, acids formed-of -two acids assimilated into
one. 'Thus Frlodhoim (1800) obtained phoBphor-vanodio acid, and SohmHss-Dumonfc
X1890) a similar taiiono-vapadto add. The former IB obtained by heating VaOs with
sJrupy photiphorio acid. The reaultant golden-yellow tabular cryatals have the
composition H9OV906P9OiiOH90, awcl there are corresponding • salts -<- for esitwnple,
(NH^)9V8Oft!P90a with 8 and 7H»0, &o, These salts cannot bo separated by crystallisa-
tion, BO tlitvt tliore are ' oomploxea' of these aoida in a whole floriea of salts (and also in
naturo), It may be flappoaecl (Priodhoim) that VjOj hero, os it were, plays the part of a
bane, or that those adds may bo looked upon as double salts. Among the true double
iBftlte of vanadium (Nb "and :T») very many are- known among the fluorides, auoh aa
VFsiNEUF, VOffaayTHiE1, tOaF,8NK4P, <feo, (Pettersson, Piodni, and §e,orgi, 1890-93).
Vanadiura was diaooverod at the beginning of this century by Del-Eioj and afterwards
Investigated by SoMriJm, but it woe only in 1808 that 'Eoscoe established tho abovo
lott»ul» of the vanadio oompoundB,
** The wBSiuraheu made by Boaooe were preceded by those of, 'Marignoo m 180U, on
th® oomyoundt of niobium and tcmtafavm, to whiolj were also ascribed different formulro
from- thoae now recognised. Tantalum was disoovwed simultaneously with vanadium
by Hutohett Kid Bkebwg, and waa ftfterward» studied by Kose, who k 1814 discovered
»toblotti to It, Notwifch»Wnditfg the numerous researches of Hermann (in-Moscow),
Kobftll^BoBe, ftttd M«4figniio, still there is not yet any certainty as to the purity of, and
thu proportion a&orilxKl to, the compounds of these elements. They ore difficult to
from ciw.li othor, and especially from the oorito metals and titanium, &o., which
thorn. Bofore tlio invostigations of Bose the highest oxide of tantalum was
i bttlwng to the type TaXa—fehab in, its composition waa token as Ta05, and to
l<wor oxido wan «,«Qtibod ft formula TaOj. Roao gave the formula TaQ3 to tho
Wgh« oxide, and discovered a now element called niobium in tho substance previously
'•tjppoiod to bti the loww oxido. He even admitwil tho oxiutonoo of a third oloaionfc occur'
ring togttl»r with tantalum and aiohiwtn, wldoh. ha named palopium, but ho affcorward»
found tlmt pnlopio Mid wtv« only luinthisr oxide of niobium, and he ccmuklorod it probable
that th« Wgher oxide of this element is Nb.Os, and the lower Nba05, Hormonn found that
wlobte ftddi whloh WM oottBitlarod pure oontolned a oonBiderable quantity of tonfcajio ad3>
nad 1»«Jd« thin he twlmlttea ihe wistonoa of another speoial metollio add, which ha called
flmenia add, nlfeur th* locality (the Itm«a m§«nta,iBB of the tfrali) of the mineral from
wWoh ht ob Wfttd li V, Kob«ll »ooga|,9ed »tUl aaother add, which he called dianlo acid,